@John Square
A is easy: The climate is changing. Always has been changing, always will.
B is a bit more tricky because the measures used for estimating historical changes are a tad shaky, especially for measuring short term changes. One of the most controversial things about the old hockey stick is that different means are used for deriving the values of different parts of the curve...
C seems to be, to say the least, on the borders of what the science can reliably offer at the moment
D well who knows...
Mind you that's not an exuse to do nothing: there are a lot of things that are sensible to do no matter in what direction and why the climate is changing.
Burning fossil fuels is a pretty damn silly idea, so the less the better. There are better things to do with the oil. Mind you all of history tells us that wind power has always been a last resort when nothing better is available... If water power can't scale without major ecological catastrophe (like a Severn barrage) then build nukes... Cut down on excess travel too..
Filling the atmosphere with soot/chemicals/other dross is a pretty silly idea too, so lets do as much as possible to stop that.
Breeding another billion people every decade or whatever is pretty damn silly too, but I don't see too much empahsis on that one...